Enhanced visualization software tools have been developed that allow for interactive display and manipulation of large-scale geometric models of various products such as models developed using Computer-Aided Design (CAD). Typically a 3D geometric model in a computer-aided design (CAD) format is selected and then converted into a 3D FEA (Finite Element Analysis) mesh model which may be evaluated using a computer-aided engineering (CAE) analysis. For example, CAE simulations are advantageous in particular types of analysis, such as safety analysis and structural analysis. Examples of CAE techniques include finite element analysis (FEA) and computational fluid dynamics (CFD).
Computer aided engineering (CAE) plays an important role in manufacturing industry, particularly in automobile and aircraft industry. The use of a CAE simulation allows for verification of a design goal and a prediction of a mechanical behavior of the design, including its systems, subsystems and components.
An important feature in CAE includes mesh deformation in the simulation of mechanical behavior of a design. Traditionally, mesh deformation is achieved through deformation of the corresponding CAD model and subsequently through remeshing the modified CAD model into a new mesh model. This approach is expensive and requires CAD experts rather then CAE engineers themselves to complete the task of CAD model modification. It is, therefore, highly desirable that a CAE engineer be able to deform an existing mesh model directly. This is known as “CAD-free” morphing. Recent developments in “CAD-free” morphing techniques have enabled FEA and CFD to be used not just for analysis of the existing design but to explore better design alternatives. For this purpose various morphing techniques have been developed to change the shape of a 3-D CAE mesh model directly.
One of the key issues in mesh deformation is how to parameterize mesh nodes for their coordinated and controlled shape transformation, such as deformation. Traditionally, parametrization is achieved through a geometric operation procedure includes such operations as point projection, line/curve intersection, and domain mapping. Despite many geometric algorithms developed for this purpose, geometrical parametrization can only handle relatively simple cases of deformation.
In order to allow more complex cases of deformation, a physics-based parametrization scheme referred to as “Dirichlet Parametrization” has been applied in prior art processes. For example, Stewart et al. (US Patent Publication No. 2003/0080957), which is hereby incorporated by reference in its entirety, disclose using a using a Dirichlet parameter distribution to determine the displacement of a surface feature. In this method, 3D mesh nodes are projected by line-of-sight onto a 2D plane to form a 2D mesh which is then used to numerically to solve a 2D steady-state heat transfer problem.
However, prior art parametrization schemes including Dirichlet parametrization have been found by the present inventors to have major limitations. For example, in prior art Dirichlet parametrization approaches, where the 2D mesh required for solving the steady state heat transfer problem is obtained by projecting the mesh surface of a 3D mesh model onto a plane, has several shortcomings. One shortcoming is that nodes representing the 3-D mesh model of solid elements or elements frequently lack line-of-sight visibility from the 2D plane being parameterized (projected onto) and are therefore not accurately reproduced in the projection process. In addition, performance and accuracy of the prior art Dirichlet parametrization processes using a projected 2D mesh also depends on the density and characteristics of the 3D mesh. For example, deformation specific parameters, such as the boundary details of a deformed region, may be poorly approximated.
One method used for deformation or changing the shape of Geometric surface features in the prior art including the use of prior art Dirichlet parametrization approaches, is known as Direct Surface Manipulation (DSM), operates by interactive editing by a CAE user of surface meshes and is useful for a variety of CAE applications. DSM is capable of deforming a mesh surface region defined specifically by the user.
In DSM, an entire surface feature represented by a mesh is placed on an existing graphics generated parametric surface as a single geometric entity. After the DSM surface feature is created, a user of the system that forms the surface feature may control the location, shape and continuity of the feature independently by adjusting interactive input parameters on a real-time basis. Advantageously, DSM provides for modifications to a mesh model without relying on CAD techniques.
Various feature-driven and parametric-driven techniques are known in the art for creating a mesh feature, such as Direct Surface Manipulation, Free-Form Deformation and the like.
While existing devices and methods suit their intended purpose, the need remains for a system and method that allows improved flexibility in altering mesh surfaces including selectively controlling a computing time as well as a quality of the resulting altered mesh.